Date Due: Thursday, 26 June 2002
The total maximum points were 60. Point distribution for each question noted below.
(5 pts - 1 each)
| 1 atmosphere of pressure is equivalent
to:
76.0 centimeters of mercury 14.7 (or 15) pounds per square inch (psi) 1013.25 (1000) millibar (mb) 34 feet of water
|
1b. The lowest recorded sea level corrected pressure in
the world was ________. [Please include units!]
| Lowest pressure: 870 mb = 25.68 inches of mercury |
| Highest pressure: 1083.8 mb = 32.01 inches of mercury |
| The range: Range = (High - Low)
= (1083.8 - 870) mb = 214 mb =(32.01 - 25.68) in = 6.33 in of mercury |
1c. What is the weight exerted by the atmosphere upon the flat,
horizontal roof of a 25 foot by 50 foot building? [Assume standard sea
level conditions; English units may be used here]. Clearly show your
work for partial credit!
| From Pressure = Weight / area,
we can determine that Weight = Pressure x area
Pressure = 15 pounds per square inch (approx.) Area = 25 ft x 50 ft = 1250 sq. ft. Since 1 sq. ft. = 144 sq. in. (count them - since 12 inches on each side of the square), then 1250 sq. ft. = 1500 x 144 = 180,000 sq. inches. Then: Weight = 15 lb per sq. in x 180,000 sq. in. = 2,700,000 lb or 1350 ton (If 14.7 psi were used, the weight would be 2,646,000 lb or 1323 ton) Note that units check too! While this answer may sound large, the roof does not collapse from the weight exerted by the atmosphere since the air pressure is pushing on the roof in all directions. |
1d. A football fan brought an aneroid barometer to Mile High
Stadium in Denver (elevation of 1 mile) and made a reading of 835 mb. What
would be the approximate sea level corrected pressure if we assumed that
the pressure decreases at approximately 1 mb per 10 meters ascent through
the atmosphere?
| Mile High Stadium in Denver is 5280
ft above mean sea level (MSL), or 1600 m MSL.
Since the air pressure is assumed to decrease at a rate of 1 mb per 10 m, the pressure at the stadium should be 160 mb less than at the mean sea level directly below the stadium. Because the observed station (or in this case, stadium) pressure was 835 mb, by descending to sea level, the pressure would increase, or at the stadium would be [840 + 160] mb or 995 mb. |
How does this sea level pressure that you calculated compare with the
standard sea level pressure?
| The sea level pressure below Denver on this particular day (995 mb) is slightly less to a typical value of sea level pressure (1000 mb) and it is 18 mb less than standard sea level pressure (1013 mb). |
2. Current Weather on the Web (6 pts.)
See http://www.aos.wisc.edu/~hopkins/aos100/homework/s02hmk1k.htm
This portion of the homework was designed to have you access current
weather and climate information from a local National Weather Service Office
on the Internet. Any "reasonable answer" that fell within the range
of values for the past week's weather in Madison was accepted.
1f. Convert the following temperature readings:
| 41 °F = 5 °C
= 278 K
-40 °C = -40 °F = 233 K 258 K = -15 °C = 5 °F Note: Be careful of signs! If the negative sign does not appear in your answer where appropriate, the answer is not correct. |
1g. The record highest temperature for Madison, WI was 107
°F (41.7 °C) on 14 July 1936, while
the record low was -37 °F (-38.3 °C) on 30 Jan 1951.
What is the range of Madison's extreme temperatures?
| Range = (High - Low) = 107 °F - (-37) °F = 144 Fahrenheit degrees. |
1h. Compare these record temperatures with those of the United
States and the world.
[Please include units!]
|
|
|
|
|
| United States | 134 °F or
56.7 °C |
-79.8 °F or
-62.1 °C (includes Alaska) -69.7 °F or
|
213.8 °F or
118.8 ° C (includes Alaska) 203.7 °F or
|
| World | 136 °F or
57.8 °C |
-129 °F or
-89.4 °C |
265 °F or
147.3 °C |
1i. The National Weather Service at Madison reported the following
information for individual days during this past January. The "normal"
high and low temperatures for these days are also included and represent
the 30 year averages for the 1961-1990 climatological interval.
|
|
Average Temperature |
Average Temperature |
| 4 Mar 2002 |
|
|
|
|
|
|
i.) Actual Heating Degree Day Units:
| HDDU = [65 °F - Average daily temperature] |
| 4 Mar 2002: 65 °F – 6 °F = 58 HDDU |
| 11 Mar 2002: 65 °F – 17 °F = 48 HDDU |
| 3 Mar: 65 °F - 15 °F = 50 HDDU |
| 11 Mar: 65 °F - 16 °F = 49 HDDU |
| Since 20 Jan 2001 was a day that was cold (daily average was +7°F ) or "below normal" temperature-wise, 58 HDDU were accumulated as compared to the "normal" of 50 HDDU. Thus, more energy than normal would have to be consumed to heat your house. However, five days later on 25 Jan 2001 the daily average of 17 °F was nearly "normal" (or 16 °F), meaning a "normal" amount of heat would be needed (other factors such as wind and sunlight that are not included in this computation would also affect the fuel consumption), since 48 HDDU were accumulated as compared with the typical 49 HDDU. |
Latest revision: 27 July 2002 (2000 UTC)
Produced by Edward J. Hopkins, Ph.D. Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison, Madison, WI 53706 hopkins@meteor.wisc.edu
URL Address: aos100/homework/s02hmk01a.html
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